[$] Transparent huge pages, NUMA locality, and performance regressions

Sometimes, the kernel's no-regression rule may not have the desiredresult. Andrea Arcangeli led a session at the 2019 Linux Storage,Filesystem, and Memory-Management Summit to make the point that the recentreversion of a fix after a performance regression was reported has led toworse performance overall - with, as is his wont, a lot of technicalinformation to back up that point. With a wider understanding of what is atstake here, he hopes, the reversion can itself be reverted.